com.kenshoo.pl.entity.spi.FieldValidator Maven / Gradle / Ivy

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package com.kenshoo.pl.entity.spi;

import com.kenshoo.pl.entity.CurrentEntityState;
import com.kenshoo.pl.entity.EntityField;
import com.kenshoo.pl.entity.EntityType;
import com.kenshoo.pl.entity.ValidationError;

import java.util.function.Predicate;
import java.util.stream.Stream;

/**
 * The simplest form of a validator - validates a single field value without using any external information.
 * For example, may be used to validate that the value of a field is positive.
 *
 * @param  entity type
 * @param  type of the validated field
 */
public interface FieldValidator, T> extends ChangeValidator {

    /**
     * @return the field validated by the validator
     */
    EntityField validatedField();

    /**
     * Validates the new field value.
     *
     * @param fieldValue new value of the field
     * @return validation error or null if none
     */
    ValidationError validate(T fieldValue);

    /**
     * @return a list of fields to fetch. May contain fields of parent entities only
     */
    default Stream> fetchFields() {
        return Stream.of();
    }

    /**
     * @return Predicate when should validate fields. It is used together with fetchFields(), so only parent fields can be referenced here.
     */
    default Predicate validateWhen() {
        return e -> true;
    }
}